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Supercritical carbon dioxide (SC-CO2) is a clean and green technology for extracting polyphenols and antioxidants from roselle (Hibiscus Sabdariffa) as nutraceutical ingredients and high-value co-products development. To increase the SC-CO2 fluid affinity towards polar compounds, general regard as a safe (GRAS) solvent, ethanol-water was added in a small amount as a modifier. Dry roselle calyces were extracted using modified SC-CO2 and conventional methods (Soxhlet and Shaking Water Bath) to determine whether the SC-CO2 technology may improve the extraction of phenolic content and antioxidant activity. The results showed that the SC-CO2 extract had a significantly higher yield of total phenolic and flavonoid content than the conventional extraction method. The conventional method produces a redder but lighter extract than SC-CO2 extraction. SC-CO2 also had a higher antioxidant activity as measured by DPPH radical scavenging. These results suggest that SC-CO2 technology increases the quantity and quality of roselle calyces’ extract. The findings increased the reliability of using this technique to produce high-value products from this high-value plant. Roselle as a low-cost sustainable local crop source, as well as SC-CO2 as a clean energy process with low environmental impact, excellent solvent recyclability, and reduced chemical use, could increase the market value of antioxidant-rich extract.

The dumping of waste banana peels from local chip manufacturing has encouraged sustainable food trends to valorize these peels as pectin sources. In this study, soluble pectin from banana peels was extracted using a continuous subcritical water extraction system (SWE). This method was a promising fast extraction process with a water solvent that was environmentally friendly. Temperature (100 to 160 °C) and extraction time (5 to 50 minutes) were manipulated, with a fixed pressure of 15 MPa, a flow rate of 15 mL/min, and a particle size of 0.6 mm. The response surface methodology (RSM) was used to generate approximately 13 experimental trials from the central composite design. Based on linear and square models, the results revealed that the interaction of temperature and time to pectin yield had a significant effect. At 100°C for 5 minutes, an optimal condition for producing pectin yield was achieved, which risen the highest pectin yield by 26%. As a result, the SWE continuous system promoted increased pectin production in the shortest extraction time. In short, banana peel pectin is a powder that serves a primary function in numerous food, pharmaceutical, and cosmeceutical applications.

Response Surface Methodology (RSM) was employed to optimize the extraction rate of phenolic and flavonoid contents from peanut skin by supercritical carbon dioxide (ScCO2) assisted by ethanol as entrainer. The studied extraction parameters were pressure (10 to 30 MPa), temperature (40 to 70 oC), and the ratio of ethanol (2.5 to 7.5%). Brunner’s and Esquivel’s models were applied to evaluate the extraction rate. The best-operating conditions, in the tested range, were 30 MPa, 40 °C, and 4.64% of ethanol ratio, with a maximum extraction rate of 0.22 mg/g.sec and 0.19 mg/g.sec of the phenolic and flavonoid content, respectively. The findings concluded that higher-pressure condition has a significant impact on the extraction rate of phenolic and flavonoid

Anthocyanins are one of the bioactive compounds in roselle that has many medicinal proposes. Anthocyanins are placed in the inner part of the roselle; therefore, combinations of two methods were applied to extract the anthocyanins. The first stage is employing supercritical carbon dioxide (ScCO2) to break the particle surface or outer layer of the roselle based on the total phenolic compounds (TPC) recovery, and the second step was to apply subcritical water extraction (SWE) for the extraction of anthocyanins. The objective is to determine the best conditions to obtain high yields of total anthocyanins compounds (TAC) from the roselle (Hibiscus sabdariffa) by employing a combination of ScCO2 and SWE. The optimal conditions of ScCO2 (first stage) were 19.13 MPa, 60 °C, and 4.31 mL/min, yielding 18.20%, and 80.34 mg/100 g TPC, respectively. The optimum conditions of SWE (second stage) were 9.48 MPa, 137 °C, and 6.14 mL/min, yielding 86.11% and 1224.61 mg/100 g TAC, respectively. The application of integrated ScCO2 and SWE proved successful in achieving high anthocyanins production and yield as compared to previous extraction methods. This approach may be used to extract the roselle with a greater anthocyanin’s concentration than the prior method.

The main objective of this study is to investigate the effect of process extraction variables (extraction time, volume of solvent, weight of sample) on the production of essential oil from ginger rhizome using Response Surface Methodology (RSM).

This study aimed to evaluate the extraction yield, and anthocyanins content of Hibiscus sabdariffa L. calyces extract using different temperatures (T) at 50 - 70°C, pressure (P) at 8 - 12 MPa, and modifier ratio at 5 - 10%.

The optimization of red pigment anthocyanin from roselle (Hibiscus sabdariffa) by subcritical water extraction (SWE) has not been the topic of a scientific investigation. Therefore, the objective of this paper was to establish the optimal parameters for obtaining the maximum yield, total anthocyanin compounds (TAC), total phenolic compounds (TPC), and total flavonoid compounds (TFC) by SWE utilizing a response surface methodology. The optimal conditions were 8.75 MPa, 393.54 K, and 4.89 mL/min, with a yield of 0.69 g/g, TAC of 927.74 mg/100 g, TPC of 39.54 mg/100 g, and TFC of 614.57 mg/100 g. High temperatures and flow rates are favorable for achieving a maximum yield. In contrast, a high temperature is suitable for obtaining high concentrations of anthocyanin, flavonoid, and phenolic compounds. This technique (SWE) recovers anthocyanin at a greater extraction rate than traditional methods; hence, SWE may be substituted for conventional methods for extracting anthocyanin.

The exclusive properties of β-cyclodextrin (β-CD) combined with its harmless characters making it as an interesting and potential carbon adsorbent for water pollutants removal via adsorption. This work was aimed at evaluating the kinetics and isotherm parameters of methylene blue dye adsorption onto β-CD polymers. The carbon polymers were prepared by citric acid cross-linking, followed by post-treatment with sodium p-toluenesulfinate. The adsorbents were characterized using TGA, BET and FTIR. The adsorption of methylene blue was studied at varying concentrations (5–300 mg/L) and contact times (10–2880 min), and the kinetics and isotherm models were employed to describe the adsorption data. The post-treated carbon polymer exhibits a greater specific surface of 16.6 m2/g. The maximum adsorption of methylene blue by cross-linked and post-treated β-CD adsorbents are 263 and 227 mg/g, respectively. The kinetics data fitted well into pseudo-first order model, indicating physical adsorption. The Boyd’s model showed that film diffusion may be the controlling mechanism. The equilibrium data of methylene blue adsorption for the two β-CD polymers obeyed Langmuir model. To conclude, β-CD is a promising adsorbent candidate for the treatment of dye wastewater.

In the current study, the solubility of potent bioactive compounds from cat’s whiskers (Orthosiphon stamineus), viz. sinensetin (SIN) and isosinensetin (ISO), is measured in ethanol-assisted supercritical carbon dioxide (SC-CO2). Experiments were conducted at temperature and pressure of 40–80 °C and 10–30 MPa, respectively. Three semi-empirical models of Chrastil, del Valle-Aguilera, and Gonzalez were used to correlate the compounds’ solubility in SC-CO2 + ethanol. The highest solubility of SIN and ISO was obtained at 3.945 and 2.323 mg/L, respectively, at 10 MPa and 80 °C. The solubility data revealed the direct effect of temperature, while the pressure has a dual effect of both increasing and decreasing the compounds’ solubility. This study revealed the influence of solute’s melting point, dipole moment and molecular structure on its solubility in SC-CO2 + ethanol system. Therefore, SIN has higher solubility in SC-CO2 + ethanol system due to its lower melting and dipole moment compared to its isomer, ISO. In addition, the solubility of the SIN and ISO data was satisfactorily correlated with all semi-empirical models, with less than 4.0% of the AARD%. The enthalpy of vaporization and solvation for SIN and ISO in SC-CO2 extraction were determined.

The aim of this study is to investigate the effect of particle sizes on yield, diffusivity, mass transfer and morphological characterization on extraction rate of rubber seed oil recovery by supercritical carbon dioxide (ScCO2). Pressure 30 MPa, temperature 60 oC and average particle size 500 µm gives the maximum oil recovery (34.71%), diffusivity coefficient (5.13 E-12 m2/s) and extraction rate (0.6 mg/sec). The morphological characterization of extracted rubber seeds was done on the basis of scanning electron microscopy which was parallel with the results of the effect of particle size. The results obtained from gas chromatography-mass spectrometry showed that the rubber seeds oil contained significant essential fatty acids and certain chemical constituents which are very valuable.

Sinensetin is a rare polymethoxyflavone that possesses strong anti-angiogenesis activity that can be obtained from Orthosiphon stamineus (O. stamineus) leaves. In this study, supercritical carbon d...

The main objective of this study was to determine the mass transfer for extraction of peanut (Arachis hypogea) skin by using drying models as alternatives extraction models. The mass transfer was measured at the pressure ranging from 10 MPa to 30 MPa, temperature of 40 oC to 70 oC, and rate of modifier 0.075 mL/min to 0.225 mL/min. The Lewis, Page, Peleg, Henderson and Pabis, and Avhad and Macetti as drying models were modified to illustrate the extraction process and to transform as alternative empirical models. An average absolute relative deviation percentage (AARD%) of Lewis, Page, Peleg, Henderson - Pabis, and Avhad-Macetti was 9.52%, 4.67%, 19.41%, 0.26%, and 0.04%. Avhad and Macetti model offered the best fitting between experimental data and modelling data. The results showed that drying model was applicable to correlate the experimental data of extraction process due to low percentage of error and high coefficient determination.

Two dimensional (2D) reduced-graphene-oxide/g-C3N4 modified 2D ZnV2O6 heterojunction for enhanced photocatalytic CO2 reduction has been investigated. The catalysts were fabricated using one-pot solvothermal method and were tested in a fixed-bed reactor under visible and UV-light. The ZnV2O6/RGO/g-C3N4 composite catalyst demonstrated excellent photoactivity for CO2 reduction to CO and hydrocarbons under visible light. The maximum CO yield rate of 2802.9 μmol g−1 h−1 was obtained over the composite, which is 7.4 and 1.7 times higher than using g-C3N4 and ZnV2O6, respectively. The improved activity attributing to synergistic effect of 2D layer heterojunction with enhanced charges separation by RGO mediator under visible light. Comparatively, 2 times lower productivity was obtained under UV-light than visible-light due to higher visible-light absorption. The time-dependent kinetic-model was further developed to understand the influence of photocatalytic oxidation and reduction processes on the reaction chemistry. The model is based on Langmuir–Hinshelwood (L–H) mechanism to understand the formation rates of products during photocatalytic CO2 conversion with water vapours. Kinetic reveals surface reaction is a rate limiting step, which depends on the generation of charge carrier with higher light absorption. The findings from the experimental and kinetic-model would be useful to understand photo-catalytic reaction engineering in solar energy applications.

This research aims to optimize a supercritical carbon dioxide extraction assisted by co-solvent ethanol for the recovery of catechin and epicatechin from peanut (Arachis Hypogea) skin. The second objective was to determine the solubility of catechin and epicatechin by semi-empirical models. The operating conditions were: pressure of 10 to 30 MPa; temperature of 313 to 343 K; and ethanol rate of 0.075 to 0.225 mL/min. Response surface methodology (RSM) was applied to determine the optimum condition to recover the catechin and epicatechin. The optimum condition was found to be 21.86 MPa, 332.23 K, and 0.17 mL/min with 752.03 µg/g of catechin and 3399.84 µg/g of epicatechin. Putra model successfully fitted the solubility of catechin and epicatechin in range of 1.21 E-5 g/L and 6.02 E-5 g/L with 3.11% of AARD (%). Application of RSM was succesful to optimize the conditions with high quantity of catechin and epicatechin.

Subcritical water extraction of pectin from banana peels are arising as a low methoxyl pectin for natural gelation agent. In this study, banana peel pectin was extracted using water as a main solvent and gelation properties tested under peak hold test and interfacial double wall ring. The best extraction condition of pectin yield retrieved at temperature (140 °C), time (5 min) and particle size (1.18 mm). The FTIR spectrum showed high of free esterified in carboxylic groups that classified as low methoxyl pectin. Gelation interaction mixture of BPP140 and 80 mM/L Ca2+ system is significantly achieved highest torque and viscosity values until reached up to 168.97 μN.m and 0.005 Pa.s. Also, this system contributed to stronger gel as the elastic moduli (G’) and viscous moduli (G”) increased to 0.170 and 0.018 Pa, respectively. Presented results proven the banana peel pectin could be an optional gelling material and applicable for various applications.

An accurate and suitable semi-empirical model is crucial to determine the solubility of plant extracts in supercritical carbon dioxide (SC-CO2) assisted by ethanol as a co-solvent. In this paper, a...

Essential oil is a kind of remedy that is originated from various part of plants. One of them is Physalis angulata Linn that is beneficial to human health yet very scarce explored by researchers. In this work, extraction of this herbal essential oils using microwave-assisted extraction (MAE) is proposed as an alternative greener extraction technique. The objective of this study is to determine the effect of extraction time (4, 6, 8, 10 and 12 min), liquid-to-solid ratio (ranging from 8 to 16 ml/g) and microwave power (270, 360, 450, 540 and 630 W) on the extraction yield of oil from Physalis angulata Linn. Results showed that the optimum operating condition of MAE of this herb that gave the maximum 21 wt% yield of essential oil was found when extracted in 12 minutes for duration of extraction time using 12 ml/g for liquid-to-solid ratio and 630 W of microwave power. GC-MS results presented the highest constituent of 4,5- Dichloro-ortho-phenylenediamine (24.07 min), Diethyl Phthalate (24.09 min) and Phthalic acid, ethyl 2-pentyl ester (24.09 min) with percentage of 4.10 %. These results demonstrated that Physalis angulata Linn essential oil possess of health beneficial phytocompounds that exhibits as antimicrobial, anticancer and anti-toxic agent.

Due to the health benefits such as anti-diabetic, antioxidant, and anti-inflammatory agents, the extraction of bioactive compounds from natural plants becomes significant. One of the favored extraction processes is supercritical carbon dioxide (SC-CO2). SC-CO2 is known as a green method with a high-selectivity process. Therefore, this study aims to determine the best parameters and mass transfer process to extract the bioactive compounds, viz. sinensetin, isosinensetin, and rosmarinic acid, in the leaves of Orthosiphon stamineus using the SC-CO2 extraction technique. Response surface methodology was applied to optimize the operating temperature and pressure of 40–80 °C and 10–30 MPa, respectively. Meanwhile, to quantify the concentration of sinensetin, isosinensetin, and rosmarinic acid, a high-performance liquid chromatography was used. Results showed that the level of sinensetin, isosinensetin, and rosmarinic acid varied significantly at each extraction condition from 122.98 to 469.54 mg/kg sample, 50.60 to 419.07 mg/kg sample, and 17.43 to 931.44 mg/kg, respectively. Based on the optimization study, the optimum pressure and temperature were 10 MPa and 80 °C, respectively, with 440.3 mg/g sinensetin, 392.9 mg/g isosinensetin, and 752.0 mg/g of rosmarinic acid concentration obtained. Meanwhile, the single-sphere model showed a significant correlation with sinensetin, isosinensetin, and rosmarinic acid extraction, with an average AARD of 12.31%, 13.72%, and 18.90%, respectively. The range of diffusivity coefficient, De, of sinensetin, isosinensetin, and rosmarinic acid was 5.47E−13–1.81E−12 m2/s, 8.26E−13–1.89E−12 m2/s, and 2.64E−13–2.28E−12 m2/s, respectively.

Every year, more than 50 million metric tons of apples are produced, and apple pomace is frequently discarded as waste in the food industry. Apple pomace, a byproduct of apple juice and cider production, is used as a sustainable raw material to make valuable products such as nutraceuticals and pectin. Apple pomace contains a substantial amount of antioxidant compounds, which have been related to several health advantages. Therefore, valuable components extracted from this byproduct may be used in the food and pharmaceutical industries. The common and new technologies to obtain valuable products from apple pomace which has come from production of apple juice or cider. Especially, emphasis of new and green technique is very important and will contribute the literature. Therefore, this review discussed apple processing, pectin as a bioactive compound, the extraction methods, current applications of apple pomace byproducts, and future studies on its potential uses in food.

The main objective of this study is to investigate the effect of process extraction variables (extraction time, volume of solvent, weight of sample) on the production of essential oil from ginger rhizome using Response Surface Methodology (RSM). A gas chromatography-mass spectrometry (GC-MS) method was employed to obtain the essential oil concentration in percentage (%) area. The RSM indicated that the weight of the sample had a major linear effect on the oil recovery while the extraction time had a major quadratic effect on the essential oil concentration in % area. The highest oil recovery and essential oil concentration in % area were 15.2% and 22.64%, respectively. The best operation conditions for the oil recovery were 4 hours of extraction time, 750 mL volume of methanol and 30 g weight of sample. The best operation conditions for the essential oil concentration in % area were 5 hours of extraction time, 500 mL volume of methanol and 30 g weight of sample.

Oil and gas operators worldwide are expecting service companies to deliver integrated techniques to minimize, if not prevent, drilling problems. Drilling fluids perform vital functions to ensure the success of drilling operations. The technical challenges often associated with water-based drilling fluids are loss of critical properties, such as fluid loss control and rheology, under demanding conditions, such as in drilling deeper, high-temperature and high-pressure wells. Fluid loss during drilling operations has a very significant effect in both reservoir formation damage and monetary terms. The use of durian rind (DR) as a new additive in controlling lost circulation would provide another opportunity to reduce waste and avoid pollution. Therefore, DR was used to improve the rheological properties of water-based mud, and it was prepared for use as a fluid loss additive. For a better understanding of the influence of pectin on drilling mud properties, the rheological evaluation of untreated DR was compared to that of mud samples containing treated DR. The pectin in DR was extracted using four different solvents, namely, ethanol, methanol, sodium hydroxide and hydrogen peroxide, and the most effective solvent to remove the pectin was then determined. The Fourier transform infrared spectroscopy (FTIR) results showed that NaOH was the best solvent for removing pectin from DR. Thermogravimetric analysis (TGA) was used to determine the thermal stability of DR before and after treatments. The TGA results demonstrated that the treated DR had improved thermal stability compared to untreated DR. The sizes of DR used were coarse, medium, and fine. The untreated DR presented better rheological properties than the treated DR. The experimental investigation showed that a concentration of 20 lb/bbl of intermediate-sized DR was the best concentration among the tested samples. Copyright © 2019 Southwest Petroleum University. Production and hosting by Elsevier B. V. Open Access CC-BY-NC-ND

Adsorbents were derived from banana peel through chemical treatment using phosphoric acid, potassium hydroxide, and sodium hydroxide to adsorb methylene blue from water. The adsorption of methylene blue was performed at varying concentrations and contact times. The equilibrium data fitted well with Langmuir equation, with a maximum monolayer adsorption capacity of 99.28 mg/g (28%). Phosphoric acid-treated adsorbent exhibits a greater capacity despite a lower affinity than the other adsorbents. A two-stage batch adsorber model was developed to optimize the adsorbent dosage for performance evaluation. Banana peel is a promising resource of adsorbent for wastewater treatment.

Over 114 million metric tons of bananas are produced each year. The peel, which accounts for roughly one-third of the fruit’s weight, is commonly discarded as waste in the food industry. For centuries, the peel has been prized for its potential to heal a host of ailments. This by-product contains a large concentration of compounds with potent antioxidants linked to several health benefits. Consequently, the extracted valuable components, such as pectin, from this by-product could be applied to the pharmaceutical and food industries. More than 13% of pectin recovery is extracted by current extraction methods, such as ultrasound-assisted extraction. Subcritical water extraction also successfully extracts the pectin with high quality of extract. This review focuses on banana production and the role of pectin. Significant factors affecting its presence within the banana peel, the extraction methods, and current extraction applications are also presented and discussed, highlighting future research into its potential uses.

Roselle petals contain high anthocyanins, a good antioxidant, and natural dark red colorants. Anthocyanins help in reducing risks of cardiovascular disease and colon cancer. But anthocyanins are easily affected by extraction process. Therefore, this study proposed a new method of extracting anthocyanins using ultrasonic-assisted extraction (UAE) from roselle petals with three extraction parameters. The extraction parameters are sample’s particle size (0.125, 0.375 and 0.625 mm), solvent to solid ratio (10:1, 15:1 and 20:1 mL solvent/g solid) and extraction time (5, 10 and 15 min). The optimization of process parameters aims to achieve the highest extraction yield of extract, Total Anthocyanins Content (TAC), and Antioxidant Activity (AA). The results show that 0.125 mm of particle size, 10:1 mL solvent/g solid, 15 min of extraction obtained the best percent mass yield (64.72%), TAC (70.97 mg/L), and AA (90.05%). Method-wise, this study showed that the ultrasonic-assisted extraction gives better quality of roselle petals extracts than the maceration extraction.

The main constituents of the extract from Hibiscus sabdariffa calyces are anthocyanins which gave intense natural red colorant and commonly used for centuries for therapeutic purposes. Supercritical carbon dioxide (SC-CO2) technique could produce high-quality extracts from plant materials as it can exploit the non-toxic character and the gas–liquid properties of the SC-CO2. This research aimed to characterise the colour and the pattern of Hibiscus sabdariffa SC-CO2 extraction. The colour was evaluated by using a CIELAB method meanwhile the presence of anthocyanins in the red colour extract was confirmed by High-Performance Liquid Chromatograph (HPLC). Two types of empirical models (Modified Brunner’s and Esquivel’s models) were used to describe the extracts obtained at series of operational parameters (i.e. pressure and temperature) at 7.5 and 10% of modifier ratio, with a total solvent flow rate of 4 ml/min. Both models were analysed using a non-linear regression method. The modified Brunner’s model shows the best agreement between experimental and model calculated data with the lowest AARD of 1.30% at 70 °C, 10 MPa, and 10% modifier ratio.

Supercritical carbon dioxide (SC-CO2) which is an alternative and green method for extraction of natural plants. Many parameters in SC-CO2 including pressure, temperature, extraction time, particle size, CO2 flowrate and composition of solvent modifiers were optimized to improve the extraction efficiencies by using a response surface methodology (RSM). RSM is a collection of statistical and mathematical techniques useful for developing, improving, and optimizing processes. To adequately resolve the above-mentioned issues, a design of experiment (DOE) is required. Recently, in providing a better decision support analysis, the necessity for a specific experimental design modelling is based on statistical methodologies via response surface. Hence, objective of this study is to review the previous studies on various innovative designs that have been employed for SC-CO2 extraction using RSM Consequently, the present paper provides an insight into RSM by scrutinizing the design, modelling, predicting, and optimizing SC-CO2 process with an acceptable accuracy for different designs of experimental work with an appropriate model that fits the desired approach of the researchers.